Flutter 错误：未处理的异常：此小部件已卸载，因此 State 不再具有上下文

Question

我正在使用authStateChanges().listen来查看用户何时登录或注销以及应用程序应将它们带到何处。 但由于某种原因，我收到以下错误。

E/flutter (29194): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct).
E/flutter (29194): Consider canceling any active work during "dispose" or using the "mounted" getter to determine if the State is still active.

我需要if (user == null)成为Navigator.pushAndRemoveUntil因为我需要从另一个页面触发dispose()

    FirebaseAuth.instance.authStateChanges().listen((User? user) {
      UserModel loggedInUser = UserModel();
      User? user = FirebaseAuth.instance.currentUser;
      //  if (mounted) {
      if (user == null) {
        print(
            '------------------------------------------------------User is currently signed out!');
        print(user);
        Navigator.pushAndRemoveUntil(
            context,
            MaterialPageRoute(
                builder: (BuildContext context) => const LoginScreen()),
            (Route<dynamic> route) => false);
      } else {
        print(user);
        print(
            '--------------------------------------------------User is signed in!');
Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (context) =>
    const loadData()), (Route<dynamic> route) => false);
      }
//}
    });

Answer 1

您收到错误是因为您使用的上下文属于不再存在的State （猜测它只是一个普通的有状态页面并且存在时间很短）。

您正在尝试做的是路由但没有上下文。 您可以使用GlobalKey来实现这一点，

然后你可以在main.dart之类的地方注册回调监听器。